A population-based assessment of avoidable hospitalizations and resource use of non-vaccinated patients with COVID-19

The coronavirus disease 2019 (COVID-19) pandemic has precipitated a prolonged public health crisis. Numerous public health protections were widely implemented. The availability of effective and safe vaccines for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) presented an opportunity to resolve this crisis; however, vaccine uptake was slow and inconsistent. This study evaluated the potential for preventable hospitalizations and avoidable resource use among eligible non-vaccinated persons hospitalized for COVID-19 had these persons been vaccinated.

This was a retrospective, population-based cohort study. The population-at-risk were persons aged ≥ 12 years in Alberta (mid-year 2021 population ~ 4.4 million). The primary exposure was vaccination status. The primary outcome was hospitalization with confirmed SARS-CoV-2, and secondary outcomes included avoidable hospitalizations, avoidable hospital bed-days, and the potential cost avoidance related to COVID-19. The study inception period was 27 September 2021 to 25 January 2022. Data on COVID-19 hospitalizations, vaccination status, health services, and costs were obtained from the Government of Alberta and from the Discharge Abstract Database.

Hospitalizations occurred in 3835, 1907, and 481 persons who were non-vaccinated, fully vaccinated, and boosted (risk of hospitalization/100,000 population: 886, 92, and 43), respectively. For non-vaccinated persons compared with fully vaccinated and boosted persons, the risk ratios (95%CI) of hospitalization were 9.7 (7.9-11.8) and 20.6 (17.9-23.6), respectively. For non-vaccinated persons, estimates of avoidable hospitalizations and bed-days used were 3439 and 36,331 if fully vaccinated and 3764 and 40,185 if boosted. Estimates of cost avoidance for non-vaccinated persons were $101.46 million if fully vaccinated and $110.24 million if boosted.

Eligible non-vaccinated persons with COVID-19 had tenfold and 21-fold higher risks of hospitalization relative to whether they had been fully vaccinated or boosted, resulting in considerable avoidable hospital bed-days and costs.